Battery isolating switch suitable



L I \I y 16, 1939- ca. ROBERTSON 2,158,428.

BATTERY ISOLATING SWITCH SUITABLE FOR USE WITH INTERNAL COMBUSTION ENGINES Filed Jan. 21, 1938 Patented May 16, 1939 UNITED STATES PATE T- oF'F-icE BATTERY ISOLATING SWITCH SUITABLE FGR USE WITH INTERNAL OOIVIBUSTION ENGINES Africa Application January 21, 1938, Serial No. 186,259 In the Union of South Africa and Great Britain February 20, 1937 7 Claims.

The present inventionrelates to battery isolati-ng switches suitable for use with internal combustion engines mounted on a vehicle to serve as a source of power for propelling the vehicle in cases where an electrical battery is associated with the engine for supplying current to electrically operated parts provided on the vehicle. The battery may be employed for supplying current to electrically operated parts which are essential to the running of the engine e. g. to the coil ignition system for supplying ignition sparks in cases where the engine is a spark ignition internal combustion engine and/or for supplying current to parts which are not essential to the runningof the engine e. g. to electric lamps and accessory parts such as indicators for traffic signalling.

The invention is especially applicable to motor vehicles driven by spark ignition "internal com- ,tbustion engines of the kind which employ an induction cell for generating the ignition sparks. The primary winding of the induction coil is generally connected in series with the battery by means of an ignition :switch on the dashboard. If this ignition switch is inadvertently left .closed when t-hecar is placed outof use for several hours the battery will gradually discharge, possibly to such an extent as to be .inefiective for starting the engine when the car is next required for use. A similar thing occurs if other parts of the electrical system are left switched on, for example parking lights. An object of the invention is to overcome this disadvantage by providing an automatic battery isolatingswitch i. e. a switch which will come into operation automatically subsequent upon the stoppage of the engine and will disconnect the battery from those circuits which may inadvertently 'be left switched on (except special circuits, such as circuits to radio sets, which it may be desirable to operate when the car is stationary), and from any other circuits Which it is desired to isolate.

An embodiment .of the invention will now be described, by way of example, reference being made to the accompanying drawing comprising Figures I and II, in which Figure I shows partly in sectionand partly in elevation, the construction of a battery isolating switch according to the invention and suitable for use on a motor vehicle arranged to be driven by an internal combustion engine, Whilst Figure TI shows a circuit arrangement including a battery isolating switch according to Figure I.

In Figure I, :2 is .a mounting plate for a battery isolating switch provided with electrical terminals 3 and 4 arranged to be bridged by a laminated contact arm 5 which is clamped between a washer 6 and a collar 1, both of insulating material, and a nut 8 which engages a threaded extension 9 of collar 1 passing through the contact arm 5 and washer 6. The assembly 5, 6, 1, B, 9 is slidably mounted on a rod l0 between two helical springs H and I2. The helical spring [2 abuts at one end against the collar '1 and at its other end against a collar l3 secured at the free end of the red It by a pin I4. The other helical spring H abuts at one end against the washer 6 and at the other end against a casing H) which contains an electromagnetic coil l6 terminating in leads H and 18.

The rod I0 passes along the axis of coil l6 and is provided, in the vicinity of coil l6,with a sleeve 1 9 of magnetic material such as soft iron so that when the coil I6 is energised by current flowing through it, the sleeve 19 and rod l9 will be drawn into the magnetic field against the compression of thehelical springs H and i2. Theend of rod I'll on the opposite side of sleeve 1 9 from the contact arm 5 is clamped to the middle of a flexible diaphragm 20, which may be of rubber, by means of a screw 2| and washer 22. The diaphragm 2|] is clamped around its periphery between the casing l5 and a cover 23 by bolts 24 and nuts 25 to form on one side of diaphragm 20 .a chamber 26 which communicates with the atmosphere through a breathing hole 21, and on the other side of the diaphragm .a suction chamber 28 which communicates with a pipe 29 which may be connected to the induction manifold IM of an internal combustion engine E. Interposed between the pipe 29 and the chamber 28 there is a ball 30 held in place against an aperture 31 by a spring 32 and an apertured disc 33 to act as a ball valve and thus to prevent loss of vacuum in the suction chamber 28 due to gradual leakage through pipe 29 when the engine E stops running or if the engine E back-fires. The suction chamber 28 is also provided with a boss 34 internally threaded at its outer end to receive a tapered screw 35 the pointed end'of which seats in a seating 36 which is provided at the upper end of a passage 31 leading to the suction chamber 28 and communicates with a passage '38 of small diameter leading to the atmosphere. The device 34-38 forms an adjustable valve by means of which the suction chamber 28 may be caused to actas a pneumatic delay device with an adjustable time period.

After the switch has been operated (in a .manner which will be described later) to cause the contact arm 5 to bridge terminals 3 and 4, and the engine E has started, a difference in pressure is set up between the chambers 26 and 28 due to the suction in the induction manifold IM and causes the centre of the diaphragm 20 to be pressed in by atmospheric pressure towards the suction chamber 28, whereby the switch is held in its closed position with the contact arm 5 bridging the terminals 3, 4. The contact arm 5 is also held in this operated position due to current, for example current from an electrical generator G driven by the engine E, flowing through coil I6 via leads I'I, I8 and causing it to exert an attractive force on the magnetic sleeve I9. When the engine is stopped, current ceases to flow through coil I6 and the pressure in suction chamber 28 begins to rise due to air leaking in through passages 38 and 31. The diaphragm 2U slowly restores to its rest position and after an interval depending upon the setting of screw 35, the contact arm 5 moves out of contact with terminals 3 and 4. Due to the provision of springs II and I2, an appreciable movement of the rod III towards its rest position may take place before the contact arm leaves terminals 3 and 4, thereby permitting a more accurate setting of the delay period.

Figure II indicates the manner in which a battery isolating switch according to Figure I may be connected in the electrical circuit of a motor vehicle which includes an internal combustion engine for propelling the vehicle, a battery B for supplying current to the electrical components of the vehicle (including a starter S for starting the engine) and a generator G arranged to be driven by the engine for the purpose of charging the battery B. SI indicates diagrammatically a switch according to Figure I Whilst S2 is a solenoid switch of standard type which is included in most starting systems for closing the circuit of the starter S. CI is a cut-out connected in the battery charging circuit in the normal manner. D is a dash-board starting switch which is fitted with three contact springs instead of the two normally provided (the added contact spring is indicated by the reference 40). A is the ammeter normally provided for indicating the total current (apart from the starting current) flowing to or from the battery B.

The dash-board switch D is provided with a contact member M at the end of the switch plunger, which connects together contact springs 40 and 42 when the plunger is depressed, thereby causing current to fiow from the positive terminal of battery B, over terminal 4, contact springs 42 and 40, lead I'I, through coil I6, and over lead I8 to earth (neglecting contacts 54 for the time being). Switch SI thereupon operates and bridges terminals 3 and 4 by the contact arm 5. A circuit is thereby completed from the positive terminal of battery B via ammeter A to terminal T from which positive leads run to the ignition coil, electric lamps and other electrical components. The lead to the ignition coil will, as usual, include an ignition switch which is closed before operating the starter. When the plunger of the dash-board switch D is further depressed, springs 40, 42 and 43 become connected together, the circuit of coil I5 is thereby maintained, and a circuit is completed over spring 43 for the coil 44 of switch S2. Switch S2 thereupon operates and bridges terminals 45 and 46 with its contact arm 41, thereby causing current to flow through the windings of starter S which thereupon rotates the engine. When the engine commences to run, the suction set up in the suction chamber of switch SI serves to hold the contact arm 5 in firm contact with contacts 3 and 4. Switch D is allowed to return to its normal oil-position when the engine has started, thereby opening the circuit of coil I6 at spring 4!] so that no current now flows through coil I6 until the engine revolutions increase suificiently as explained later.

The voltage of generator G increases with the engine speed until at a certain voltage the current flowing through the shunt coil 48 of the cutout CI has risen sufficiently to cause the cut-out contacts 49 to close, whereupon a circuit is completed from generator G to terminal T which is connected to the ignition and lighting circuits and is extended via ammeter A and terminals 3, 4 bridged by contact arm 5 to complete the charging circuit for the battery B. The current flowing through the series coil 50 of the cut-out CI assists in holding contacts 49 firmly closed.

An additional cut-out C2 is connected between generator G and lead I! so that coil I6 will be energised by current from the generator G when coil 5| of the cut-out C2 becomes suificiently energised to close contacts 52. It will be noted that contacts 52 are open while the engine is being started, so that battery B is prevented from discharging through generator G in a circuit extending over terminal 4 and contact springs 42 and 40. Instead of providing cut-out C2, the same eiTect may be obtained by providing additional contacts 53 in cut-out CI in the position shown.

As long as the engine is running normally, the battery isolating switch SI is maintained operated both by the suction created in the suction chamber 28 from the induction manifold due to the movement of the pistons of the engine and by the current flowing through coil I6 due to the rotation of the generator by the engine. Should the suction decrease due to the throttle of the engine being widely opened, the switch SI would be maintained operated by the magnetic pull exerted by coil I6 on the magnetic sleeve I9; conversely if the speed of the engine should fall to such an extent that coil I6 is no longer energised, the switch SI would be maintained operated by increased suction from the induction manifold. The delay period of the switch.- SI is adjusted at the screw valve 35 (Figure I) to a suitable value, which in any case is made sulficiently long to prevent the switch SI isolating the battery due to momentary stoppages of the engine, for example due to the engine stalling in traffic.

Arrangements may also be provided for closing and/or opening the battery isolating switch by separate controls from those described, for example it may be closed by means of a separate circuit including a dry battery or by a hand operated vacuum pump or by a hand operated lever with spring control acting on the rod I0. It is advantageous to provide a hand control for opening the battery isolating switch as it will then serve as an emergency control if a short-circuit should accidentally develop in normal use of the vehicle; in this case it is not necessary to provide a switch in the ignition circuit because the engine can be stopped by the hand control opening the battery isolating switch.

It is also advantageous to provide a lock switch in the initial energising circuit of the battery isolating switch SI as indicated at 54 in Figure II. After the switch SI has been closed and the engine has been started, the lock switch 54 may s id battery to said components, b t ry isolatin contacts in said lead. an electromagnetic coil for be opened without causing the engine to stop. If the engine is stopped for a period which is less than the delay period of .the battery isolating switch S1 for example at a traflic signal, it may be restarted without touching the lock switch :54

because battery B will still be connected :to contact .46 via the .switch arm 5 and terminals 3, .4. If, however, the engine is allowed to stop for a period which is greater than the delay period of the battery isolating switch S! for example by parking the vehicle in the street for an extended period, the battery isolating switch will open and disconnect battery B from contact 46 on the switch S2 with the result that the engine can now no longer be started by an unauthorised person depressing the switch D but only by a person having a key suitable for closing the lock switch 54.

In cases in which no starter is provided, the starting switch D and the switch S2 will be omitted; the switch SI will then be operated initially due to suction set up in the induction manifold during the process of starting the engine by hand. It will then be held operated both by suction from the induction manifold and by current flowing through coil l6 as already explained.

In the case of vehicles provided with a foot pedal for controlling a starter of the pre-meshing type so that the starter pinion engages the fly wheel before current is supplied to the starter, the switch D would be arranged to be operated by the foot pedal.

Instead of the pipe 29 being connected to the induction manifold of the engine it may be connected to any other chamber of the vehicle mechanism, the pressure in which is reduced (or increased, provided that slight modifications are made to the switch construction) below (or above) the pressure of the atmosphere when the engine is started. For example, in the case of a vehicle driven by a compression ignition engine and provided with vacuum assisted brakes, the pipe 29 may be connected to the exhausting chamber of the exhauster which is driven by the engine.

I claim:

1. An automatic battery isolating switch comprising battery isolating contacts, a movable rod for closing and opening said contacts and including a magnetic portion, an electromagnetic coil adjacent to said magnetic portion, a flexible diaphragm attached at its centre to said rod and held stationary at its periphery, a pneumatic chamber of which said diaphragm forms a wall, and an adjustable leakage valve fitted to said chamber.

2. On a motor vehicle, an engine, an electrical generator coupled to said engine, electrically operated components on said vehicle, a battery for supplying current to said components, a lead from said battery to said components, battery isolating contacts in said lead, an electromagnetic coil for controlling the closing of said contacts, a momentarily operable switch for initially completing a circuit to said coil "from said battery, a. circuit for subsequently energizing said coil from said generator for automatically maintaining said contacts closed during the running of the engine, and a delay device for maintaining said contacts closed for a predetermined interval after the stoppage of the engine.

3. On a motor vehicle, an engine, an electrical generator coupled to said engine, electrically operated components on said vehicle, a battery for supplying current to said components, a lead from controlling the closure oirsaid contacts, a momentarily-operable cwitchzior initially completing .a circuit to said poll :from said battery, a circuit for subsequently energizing .said .coil from said generator :for automatically maintainin {Said contacts closed during the running of the engine, a fluidppressure chamberv :in which a pressure change is .set :up due to the starting of the .engine,

means for permitting :the pressure in said chamber to restore towards its original value upon the stoppage of the engine, and means for maintaining said contacts closed until the pressure in said chamber reaches a predetermined value during its restoration towards its original value.

4. On a motor vehicle, an engine, an electrical generator coupled to said engine, electrically operated components on said vehicle, a battery for supplying current to said components, a lead from said battery to said components, battery isolating contacts in said lead, an electromagnetic coil for controlling the closure of said contacts, a starting switch for initially connecting said coil to said battery for causing said coil to close said contacts, cut-out contacts which are closed only when the voltage of said generator reaches a predetermined value, a circuit including said cut-out contacts for subsequently energizing said coil from said generator for automatically maintaining said battery isolating contacts closed during the running of the engine, and a delay device for maintaining said battery isolating contacts closed during the running of the engine for a predetermined interval after the stoppage of the engine.

5. On a motor vehicle, an engine, an electrical generator coupled to said engine, electrically operated components on said vehicle, a battery for supplying current to said components, a lead from said battery to said components, battery isolating contacts in said lead, an electromagnetic coil for mined voltage, additional cut-out contacts, a sec- 0nd cut-out coil arranged to close said additional cut-out contacts when the voltage of said generator reaches a predetermined value, a circuit including said generator, said additional cut-out contacts and said electromagnetic coil for subsequently energizing said electromagnetic coil from said generator for automatically maintaining said battery isolating contacts closed during the running of said engine, a fluid pressure chamber in which a pressure change is set up due to the starting of said engine, means for permitting the pressure in said chamber to restore towards its original value upon the stoppage of said engine, and means for maintaining said battery isolating contacts closed until the pressure in said chamber reaches a predetermined value during its restoration towards its original value.

6. On a motor vehicle, an engine, an electrical generator coupled to said engine, electrically operated components on the said vehicle, a battery supplying current to the said components, a lead from said battery to said components, battery isolating contacts in said lead, an electromagnetic coil for controlling the closing of the said contacts, a momentarily operable switch for initially controlling the closing of said contacts, a momentarily operable switch for initially completing a circuit to said coil from said battery, a key actuated switch in said circuit, a circuit for subsequently energizing said coil from said generator for automatically maintaining said contacts closed during the running of the engine, and a delay device for maintaining said contacts closed for a predetermined interval after the stopping of the engine.

GILBERT ROBERTSON. 

